The present invention relates to a magnetic disk apparatus for recording and reproducing data out of a magnetic disk and, more particularly, to a device for driving a magnetic head included in the apparatus for writing and reading data out of of the disk.
A magnetic disk apparatus or similar magnetic data recording and reproducing apparatus is extensively used and includes a device for driving a magnetic head which writes and reads data out of a magnetic disk. It is a common practice with this kind of device to mount the head on a rotary carriage. While a magnetic disk spins at high speed, the head writes or read data in or out of the disk while rising above the disk due to a pneumatic pressure generated by the spinning disk. The head includes a servo head for reading a positioning pattern stored in the disk. The carriage is brought to a predetermined position by a servo loop based on the positioning pattern read out by the servo head. Today, a carriage positioning speed, i.e., a seek time shorter than 10 milliseconds is available. Various approaches have been proposed to reduce the overall size of the magnetic disk apparatus and increase the recording density of the disk. For example, the recording density may be increased by increasing the bit density of tracks or by increasing the track density, i.e., reducing the track width. Recently, even a track width smaller than 10 microns has been achieved.
With the conventional approaches, however, it is difficult to miniaturize the head driving device and, therefore, the magnetic disk apparatus without degrading the writing and reading ability of the head.